Answer:

Explanation:
To convert atoms to moles, Avogadro's Number must be used: 6.022*10²³.
This tells us the amount of particles (atoms, molecules, etc.) in 1 mole of a substance. In this case it is the atoms of potassium. We can create a ratio.

Multiply by the given number of moles: 15.2

The moles of potassium cancel.

The denominator of 1 can be ignored.

Multiply.

The original measurement of moles has 3 significant figures, so our answer must have the same. For the number we calculated that is the hundredth place. The 3 in the thousandth place tells us to leave 5.

In 15.2 moles of potassium, there are <u>9.15*10²⁴ atoms of potassium.</u>
You would use the formula for Boyle's Law:
(P1) (V1) = (P2) (V2)
(101.5) (2.0) = (P2?) (.75)
*P2 = 270kPa (You're allowed 2 significant figures)
P = Pressure
V = Volume
It is c: a conductor that operates only at low temperatures
Most likely the answer is water and a salt. When a strong acid and strong base react the OH and H form water and the cation from the base and anion from the acid forms a salt. I hope this helps. Let me know if anything is unclear.